Holley 950 Ultra HP Carb

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Tom68
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Re: Holley 950 Ultra HP Carb

Post by Tom68 »

USMC_Spike wrote: Wed Mar 08, 2023 8:46 pm @ Tom68, "Carby?" Really? You're starting to sound like
my little girl talking about something Sponge Bob square pants would say
or maybe Patrick the starfish.


--thx Spike
You need to hear it with the Australian accent to get the full effect.
Ignorance leads to confidence more often than knowledge does.
Nah, I'm not leaving myself out of the ignorant brigade....at times.
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juuhanaa
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Re: Holley 950 Ultra HP Carb

Post by juuhanaa »

After the engine get to temperature, the fountain of fuel stops.
It affects the oil temp and your cam event timing



-juhana
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HQM383
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Re: Holley 950 Ultra HP Carb

Post by HQM383 »

USMC_Spike wrote: Wed Mar 08, 2023 8:46 pm After the engine get to temperature, the fountain of fuel stops.

--thx Spike
Maybe most of the fuel is evaporating as it gets to temp.

I see on the dyno sheet on the first page of this thread it is dated September 2015. It states Holley 950 Ultra. Curious what this engine has been doing all this time. Trying to understand if throttle shafts are leaking due to wear and tear from a lot of use or poor quality new carb?
I’m a Street/Strip guy..... like to think outside the quadrilateral parallelogram.
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Re: Holley 950 Ultra HP Carb

Post by USMC_Spike »

Well, I was disgusted so much when after in stalling the engine, they screwed it up so much
it didn't run right. They impounded the car and engines (new and old) and presented me with a
bill 3 to 4 times more then we agreed to. Consulting with my attorney, he set me straight, pay
whatever I have to, to get the car out of impound, as it is worth much more then the higher bill.
The crooks Rico and Son, were hoping I wouldn't come up with the money and while they jacked up
fees, daily fees, lot fees, etc. etc, they would keep the Chevelle as damages for non payment, etc.
I had to have the car towed back to the home I was so frustrated, and bummed out, there is sat for
a few years. Essentially everything Rico and Son did, has to be re-done. The chassis stuff, the
eBrake, there is vacuum leak that I can't find somewhere in the engine, and on and on.

I did get the engine running after that with the help of a guy with more experience in these things
than I have. That worked for about a year maybe two. I removed the gas tank to clean it, when I did
I tore my right knee medial meniscus. I was looking to reinstall it, because I'm not sure about the
tanks inc tank I got to replace it with. It has 3/8 line and I need 1/2 inch, I could get away with 5/16 inch
that is OEM if I don't do anything crazy driving.

Life happens when you least expect it, etc, little girl growing up, trying to get Vizard and Walter's to man up
and do what's right. Even if they would fly someone down here for a day or two, to get things in order.
That, i asked who they know in north Texas who could assist me. Rico and Sons tried to adjust the valves and only
did the passenger side, etc.

You don't want to hear my sob story, there is more to it than that.

I'm here trying to fix the carb and get the engine running again.
I use a 5 gal gas can to run the engine.
I need to figure out how to reinstall (freshly cleaned) gas tank.
Purge the lines etc. New fuel filters, eventually new steel lines.
Just a lot of stuff to do, that is super hard as the chevelle sits in drive way
with about 30 - 45 degree down angle.

Oh the joy. Other wise finish up carb and give it a get go.

The important thing is I'm moving in the right direction.

--thx Spike
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1980RS
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Re: Holley 950 Ultra HP Carb

Post by 1980RS »

Monza355 wrote: Tue Mar 07, 2023 5:40 am
1980RS wrote: Mon Mar 06, 2023 11:45 pm I have one of the early 950hp Holley's with the non-replaceable air bleeds and it works great, as a matter of fact perfect. Everyone I have let try it wants to buy it but I am hanging on to that one. I had a chance to test a newer one this past year, ran like crap, was out of the box settings. Hesitated like a mo-fo. Put mine back on and the car ran great again.
What’s the part number on that carburetor ? And do you have a picture of the main body ?
The part number on my 950hp is 80496, here are a couple of pictures of it
20150308_031110.jpg
20150308_031100.jpg
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Re: Holley 950 Ultra HP Carb

Post by steve cowan »

1980RS wrote: Thu Mar 09, 2023 8:09 pm
Monza355 wrote: Tue Mar 07, 2023 5:40 am
1980RS wrote: Mon Mar 06, 2023 11:45 pm I have one of the early 950hp Holley's with the non-replaceable air bleeds and it works great, as a matter of fact perfect. Everyone I have let try it wants to buy it but I am hanging on to that one. I had a chance to test a newer one this past year, ran like crap, was out of the box settings. Hesitated like a mo-fo. Put mine back on and the car ran great again.
What’s the part number on that carburetor ? And do you have a picture of the main body ?
The part number on my 950hp is 80496, here are a couple of pictures of it

20150308_031110.jpg20150308_031100.jpg
Those older 750,850,950 carbs are brilliant, I sold a nice 850 20 years ago,wish I still had it.
These mass produced carbs today are rubbish.
steve c
"Pretty don't make power"
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Re: Holley 950 Ultra HP Carb

Post by USMC_Spike »

1980RS wrote: Thu Mar 09, 2023 8:09 pm The part number on my 950hp is 80496, here are a couple of pictures of it
20150308_031110.jpg 20150308_031100.jpg
That's a good looking carb, 1980RS seems you sorted it out also.
not being used and sitting in the bin? Did you want me to try it out
on my engine?

When you get the chance, can you measure the following:
Idle Air Bleeds
High Speed Bleeds
The Squirter size.

Do you recall what sizes(s) for your e-holes (3,4, or 5) and PVCR?

Anything else that would help me out?

--thx Spike
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Re: Holley 950 Ultra HP Carb

Post by USMC_Spike »

UPDATE:

Blue thread locked the e-hole blocked set screws.

Remeasured now that I found my - pin gauges.
The IFRs were larger than I thought, must have some
of the micro drill bits mixed in the case that I measured with.

IFRs measure .038"- with the minus pin gauge.
IFR = .039" is what that means.

So yes, .029" was indeed small. Glad I didn't start
making a batch of .029" set screws.

I will make two pair of each IFR, including:
.039"
.036"
maybe a .033

I'll follow tuners procedure for drilling these, shouldn't take too long.

QUESTION:
Is it worth while to blue threadlock the other e-hole restrictions?
They do have that interference fit with their shoulders, unlike the
ass set screw that screw right into the holes.

--thx
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Re: Holley 950 Ultra HP Carb

Post by USMC_Spike »

UPDATE

Managed to make 4 brass 6-32 .039 e-hole type set screws for the IFRs.
Not doing more unless there are other issues.
Had fun, Broke dill bit (the one I needed.)
Two of the screws got lost, fell to ground and hid,
so I'm 4 of 6 for 66%.

So for now I'm finished and will continue tomorrow.
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Re: Holley 950 Ultra HP Carb

Post by stealth »

Time to just buy the right carb from a reputable builder...

You already have a ton of money in the car.. the right carb will let you enjoy it.
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Re: Holley 950 Ultra HP Carb

Post by rgalajda »

I believe the 950 Ultra HP that 1980RS has is the older version that is a zinc casting having a 1.376 inch venturi with a 1.750 throttle bore.
Yours is aluminum casting . You should measure the venturi bore while it is apart because I believe it is a 950 Ultra XP with a 1.600 venturi and 1.750 throttle bore. The smaller venturi carb may be better suited for street use.
If I am correct his air bleeds sizing may not match up to your carb.

I lubricate all the gaskets , o-rings and threads during assembly. The centre front and rear baseplate screws can have thread sealer applied. Throttle plate screws require threadlock .
Measure your pin gauges with a good vernier caliper to sort them out.
Any bleeds with interference fit do not need threadlock.
When I tap for threads ( set screws ) I leave a shoulder/seat for the set screw to seat onto. I mark my taps for the depth. If you are using the correct length set screws , this is attainable.

The surface on the main body to metering block should be checked for flatness with a straight edge and feeler gauges , corner to corner , side to side with about .006” maximum. Usually at the screw holes will be raised from over tightening . Flat file to repair.
Also check accelerator pump cover for warpage by laying it on the fuel bowl without diaphragm and inserting feeler gauge all around . Again about .006” maximum. If warped , lay cover on flat surface with emery cloth and sand till flat . File across surface of fuel bowl if threads have been raise from over tightening.
Your new needle and seats will have new o-rings on them. Lubricate threads and o-rings.

Tuner is correct about fuel pressure at 6 psi. ( I said MAXIMUM 7.5 psi )
I always set the secondary throttle plates to about 1/4 turn past closed so no binding occurs. This is what Tuner was implying. I believe your carb was set differently out of the box. For street use about 1/4 turn will be best.
The goal here is to see if this motor will idle with more than 5” vacuum. Base timing will be important.

Tell us the size of your air bleeds , PVCR, pump cams etc.
Pinning every orifice is necessary on a used carb in case someone has previously drilled.
Don’t know what the dry float level should be on this carb, maybe someone can help but check there is no binding and springs are attached properly. Below is ( pics ) baseline settings for brass float older carbs.

I’m sure I have forgotten something as I am kinda busy now. Hope this helps though.
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Re: Holley 950 Ultra HP Carb

Post by Tuner »

The 1.600" venturi has a spooky booster signal, but ? ? here goes.

I suggest .033" IJ .070 IAB #82 PMJ .070 PPVCR #92 SMJ (no SPV) use the O2 sensor and seat of the pants and adjust as required.

If I recall correctly, you listed PMJ as #93 and PIJ as .039" with .070" PIAB ?? That would be extremely rich I think.

(edit: almost forgot) '69 Camaro manual trans 482 BBC 250 @.050 with a "1000 CFM" Holley 1.561" venturi, standard two hole .026" emulsion, the main started so soon in the very small throttle opening level ground very slight acceleration low RPM it would slobber a rich spot and tuning the idle circuit and fiddling the MJ and float level wouldn't fix it. The cure was to drop the PMAB to .025" (coincidentally, the size in early OE 3310 and L-88 carbs)

Two things in carb urban lore that just won't die are lack of understanding of the action of the main air bleed and idle jet.

1: "Bigger Main air bleed makes it leaner" is the opposite of what it does at the start of main flow. The MAB and emulsion air push the fuel up the main well at the start of flow and because an emulsion of air and fuel have less viscosity than fuel alone flow is increased. A larger MAB might make it leaner at the top, but the richness at the bottom might get "fixed" with a small MJ and that will be lean at the top.

2: Folks just don't seem to understand that the idle jet reverses at large throttle opening when the lowest pressure in the carb moves up to the venturi so booster and main well have lower pressure than IAB and IJ ... so at WOT air flows back through the idle jet and leans the WOT. A larger IJ richens the idle-off idle transition small throttle and leans the WOT when the flow reverses. This of course depends on the size of the IAB. A small IAB which is smaller than the idle jet, like in the secondary of a vacuum secondary carb, reduces the leaning effect of air flow through the IJ at WOT.
Last edited by Tuner on Fri Mar 10, 2023 2:26 pm, edited 2 times in total.
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Re: Holley 950 Ultra HP Carb

Post by Elroy »

Tuner wrote: Fri Mar 10, 2023 1:25 pm The 1.600" venturi has a spooky booster signal, but ? ?
Can you explain? I currently have one that doesn't run right.
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Re: Holley 950 Ultra HP Carb

Post by USMC_Spike »

@rgalajda, @Tuner,

I will go back through and follow as you suggest. In the mean time, here are the metering specs for the carb.
See attached.
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Re: Holley 950 Ultra HP Carb

Post by Tuner »

Elroy wrote: Fri Mar 10, 2023 2:01 pm
Tuner wrote: Fri Mar 10, 2023 1:25 pm The 1.600" venturi has a spooky booster signal, but ? ?
Can you explain? I currently have one that doesn't run right.
LOL "doesn't run right" covers a lot of territory. Every carburetor I see "doesn't run right" in the sense that everything can be improved in some way, large or small. :D


I haven't had one of these in my hands, so I am repeating hearsay. What I am told by folks who have had them on a flow bench is, particularly with the down-leg booster, the signal doesn't increase at the same rate as required by the increase in air flow and the result is it doesn't require a lot of "Too Much Emulsion" to cause the A/F to trend lean as WOT RPM increases, so a jet big enough for high RPM is too big at low RPM. The stronger signal of an annular booster works better in this body with the 1.600 ID venturi.
Last edited by Tuner on Fri Mar 10, 2023 2:40 pm, edited 1 time in total.
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